One of the most common criticisms you hear when Apple or Google publish how big their mobile app selections are is that most of the apps are junk.

"We don't need another fart app," people say.

That's correct.

Out of the hundreds of thousands of apps available on iOS and Android, there are likely only a handful you're willing to use on a regular basis. These are the apps you want.

And that's the problem with the two mobile operating systems battling it out for third place right now: Microsoft's Windows Phone 8 and BlackBerry 10. Chances are those platforms don't have the apps you want and will miss out on whatever the next hot app is when it first launches.

This week we learned from AllThings D that Netflix has no plans to make an app for BlackBerry 10 devices. The company doesn't think BB10 will have enough users to encourage more people to buy a new Netflix subscription or appease the minimal number of current subscribers who do get a BB10 phone.

This follows the news from a few weeks ago that Instagram won't appear on BB10 either. (However, there's still a chance the Android version of Instagram could be ported to BB10, but we haven't heard anything official on that yet.)

By now it's become an established trend for developers to ignore any operating system but iOS or Android.

The problem is there aren't enough people using Windows Phone or BB10 to make it worth it for developers to spend the kind of human and monetary resources necessary to bring their apps over. I've had countless developers tell me the same story over the years. They almost always make their apps for iOS first, then move to Android, and then consider other platforms if time and other resources permit. (The latter almost never happens though.)

It's not because those platforms stink. Far from it. Both Windows Phone 8 and BB10 are really great operating systems and make a strong alternative to iOS or Android.

It's because compared to iOS and Android, next to no one uses Windows Phone or BB10. Here are the latest ComScore data on smartphone market share if you don't believe that.

And it's not just the little developers ignoring the alternative operating systems. There are several big companies with plenty of resources that haven't developed for BB10, Windows Phone, or both. That's a big blow to those platforms because a solid app selection is one of the biggest draws to a new phone.

Facebook is probably the best example. It's likely one of the first apps anyone will download to their phone, but the Facebook app for Windows Phone and BB10 are actually made by Microsoft and BlackBerry, respectively. Facebook apparently didn't think it was worth its time to make two more versions of its app for platforms very few of its users would end up using.

Yes, the Microsoft- and BlackBerry-built versions of Facebook are fine, but there's no guarantee you're going to get new feature updates as quickly as you would if you were using a version made by Facebook. iOS and Android users don't have to fret about that.

On the upside, there are a handful of major developers that have said they are "committed" to making apps for Windows Phone or BB10. BlackBerry rattled a bunch of them off when it first unveiled BB10 in January, and Gizmodo has a good list of what you can realistically expect.

On the other hand, "committed" means nothing until the app appears in the platform's app store. For example, Pandora said last October it'd have an app for Windows Phone by "early 2013." That time frame is slipping away.

BlackBerry and Windows Phone fans will argue that this could all change.

Consumers could have a change of heart and start buying Windows Phones and BlackBerrys like crazy. That will entice developers to start taking those platforms seriously.

But that feels like a longshot at best. It's a classic chicken-or-the-egg problem. Developers want a platform with a ton of users and consumers want a platform with a ton of apps. iOS and Android are the only sure things right now.

The evidence is stacked against people making the switch to BlackBerry or Windows Phone at scale. Windows Phone has been around for about two and a half years, yet it's still struggling to get major developers on board. BB10 is so new it's not even available in the U.S. yet, but as good as the operating system is, it still feels too late to the game. BB10 has a bunch of cool features, but nothing enticing enough to cause people to switch over in droves.

It's easy for fans of either Windows Phone or BlackBerry to suspend belief and say the apps are coming to their platforms. But when you look at the evidence so far, there's no reason to truly think that's the case.